The present invention is an electropolishing process and device for electropolishing an inner surface of a long tube, especially applied to a long tube having a length greater than two meters and an inside diameter having a range between 0.3 to 5 cm.
A process of electropolishing includes connecting a workpiece to an anode and a metal to a cathode. Aforesaid structure of the workpiece connected to the anode and the metal connected to the cathode is put into an electrolyte for electrifying with a direct current to remove the defects on the workpiece surface and make the surface shiny and smooth. Electropolishing improves surface cleanness, roughness, passivation, etc. For different fields of semiconductor, chemical industry, biochemical engineering, food industry, tubes are needed to deliver fluids of those fields. Inner surfaces of tubes are treated by polishing or electrolysis to approach high cleanness and anti-corrosion. Especially, products of IC/LCD/III-V require high standards of cleanness and anti-corrosion, thus, applying the present invention to the products is a challenge.
U.S. Pat. Nos. 4,826,582 and 4,849,084 used part of the technologies of electropolishing a 10-meter heat exchange tube. The electrode device for positioning the workpiece and sealing the electrolyte is required. The prior art adopts a 3-layer structure of delivering electrolyte of high pressure air, but unfortunately the structure is very complicated and only suitable for the larger diameter workpieces, not for the tube of inside diameter under 3 cm.
In U.S. Pat. No. 5,958,195, which taught the technology of electropolishing an inner surface of a long and bended tube. However, to electropolish a bended tube, electrode must move alone a bended curve so as to not cause a short circuit. The most important parts are a flexible electrode and an insulation device. The insulation device avoids short circuit and non-concentricity, but this kind of device blocks a flow of electrolyte and makes a non-uniform electric field.
U.S. Pat. Nos. 4,601,802 and 4,705,611 offers a fixture applied an inside tube, and the fixture stabilizes a plurality of axially rotating tubes simultaneously. An end connector can circulate tube and exhaust gas from an upper end, and electrolyte can be recycled after overflowing. An electrode length is equal to the tube length, therefore a huge space and a super power supplier are needed to fit such conditions.
Based on the aforesaid issues, the present inventor of the patent has being studied and referred to practical experiences and theory for designing and effectively improving the prior arts.
The first object is to offer an electropolishing process and device for electropolishing an inner surface of a long tube, which improves an electrode design and applies theories of macro and micro polishing to an electrode for improving a manufacturing rate for both smoothing and passivation effect on the surface of workpiece.
The second object is to offer an electropolishing process and device for electropolishing an inner surface of a long tube, which can treat an inner surface of a tube greater than 2 meters and an inside diameter range of 0.3 to 5 cm. The device is simple to reduce equipment costs.
The third object is to offer an electropolishing process and device for an inner surface of a long tube, which avoids short circuiting and non-concentricity problems. An electrode of the present invention is installed through a center of a partition, so the electrode has a certain distance with the inner surface in tube because the partition supports the electrode. Therefore, the short circuit and non-concentricity are solved. Further the average electric field is kept all the time because the partition is round.
The fourth object is to offer an electropolishing process and device for electropolishing an inner surface of a long tube, which electrode can be designed to have multiple sections. Thereby, eliminating the need for a huge storage space. Further, the electrode can be added to different sections depending on needs to improve electrolyzing and polishing result.
The appended drawings will provide further illustration of the present invention, together with description; serve to explain the principles of the invention.